1. Field of the Invention
The invention relates to cartridges containing wound lengths of material such as, for example, ribbon cartridges, and more particularly to ribbon cartridge hubs and to latch mechanisms for retaining such cartridges on thermal or impact printing devices such as printers, typewriters, copiers, and facsimile machines, and in particular on portable printing devices.
2. Description of Related Art
In one type of thermal printing technology, a thermal printhead presses a donor film ribbon, housed in a ribbon cartridge, onto the surface of a copy sheet. When the ribbon cartridge is expended, it can be removed from the printing device and replaced by a substitute ribbon cartridge. Because the ribbon capacity of such ribbon cartridges is relatively low, replacing the cartridges is necessary frequently.
Conventional designs, used in typewriters and printers, require an operator to actuate a lever-based latch to disengage the spent ribbon cartridge from its support. After removing the spent ribbon cartridge and installing a new ribbon cartridge on the support, the operator must re-actuate the lever-based latch to secure the new cartridge onto the support. Such designs require a good degree of manual dexterity and are susceptible to damage from improper use.
An alternative design uses spring-loaded latching features on the end of a mandrel over which the hubs of the ribbon cartridge is inserted. An operator must maintain fairly accurate alignment between the cartridge and two mandrels, while pushing the cartridge with sufficient force to overcome the latching force created by the latching features. This design also requires high manual dexterity to operate correctly and is also susceptible to damage from improper use.
A need has arisen, therefore, for a ribbon cartridge and latch mechanism allowing an operator to more simply remove and replace a ribbon cartridge and providing a more robust design, less susceptible to damage from improper use.